Avermectin compounds (formerly referred to as C-076 compounds) have been known for a considerable period of time as highly active antiparasitic agents in animals including humans. See U.S. Pat. No. 4,310,519 to Albers Schonberg et al., describing the isolation of the avermectin compounds from a fermentation broth. Many derivatives of avermectin compound have been prepared and described in the literature. One derivative in particular, the 22, 23 dihydro derivative has been prepared and has found considerable commercial success as antiparasitic agents against internal and external parasites of animals. That derivative is known as ivermectin and is disclosed in U.S. Pat. No. 4,199,569 to Chabala et al. Other derivatives have been described such as the 13-polyalkoxy avermectin compounds disclosed in U.S. Pat. No. 4,587,247 to Linn et al.